Based upon the Pearson Type VIII distribution function,
a general retention function which relates the saturation to
the capillary pressure in disturbed soils has been discovered.
This simple and yet complete function has been
shown to describe precisely the imbibition as well as the
drainage branch of the retention curve....
A number of investigators have proposed equations to predict
the permeability of porous media. Most of their equations are based
on the distributions of the sizes of the various contributing pores in
the medium. Presently the pore size distributions of agricultural
soils are most commonly obtained from soil water release...
The work reported herein was performed under the annual allotment from the Office of Water Resources Research to the Oregon Water Resources Research Institute. Funds were available over a three year period, but due to difficulty in acquiring graduate students, the total time spent on the project was only 21...
Groundwater contamination on irrigated land is of concern in this nation
and around the world. In order to reduce the potential of groundwater
contamination by agricultural practices such as irrigation, fertilizer and pesticide
application, vadose-zone monitoring and sampling are needed. The main
objective of this study was to evaluate impacts...
Prevention of groundwater contamination by agricultural
chemicals requires an understanding of the complex
processes that control pesticide movement below the soil
surface. Through this understanding it is possible to try
to predict which areas may be most vulnerable to
contamination. The many models that have been developed to
characterize pesticide...
Declared out of print March 2010. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
Estimating the hydraulic conductivity of earth materials is important for many water resource modeling efforts, including predicting the transport of pollutants in ground water, computing surface runoff for flood control, and computing water budgets. This research implicitly used topography, soil, and climate data to estimate plausible continuous hydraulic conductivity values...
The Oregon Water Quality Decision Aid (OWQDA) is
a first-tier screening tool that allows you to make a broad
determination of the likelihood that a specific chemical,
when applied to a specific Oregon soil, will move through
the soil and contaminate groundwater. This determination
is called the groundwater vulnerability rating.